JP6801876B2 - Plunger lubricant composition - Google Patents

Description

The present invention relates to a plunger lubricant composition, and more particularly to a plunger lubricant composition applied between the outer peripheral surface of the plunger tip and the inner peripheral surface of the injection sleeve in die casting or the like.

Conventionally, in die casting for molding a molten metal such as aluminum, a lubricant composition has been used for the purpose of reducing friction between the outer peripheral surface of a plunger tip and the inner peripheral surface of an injection sleeve.

Since a metal melt (molten metal) heated to a high temperature is used for die casting, the plunger tip and injection sleeve that come into direct contact with the molten metal also become hot. As described above, under high temperature conditions, the lubricity of the lubricant composition consisting of only the oily base oil component tends to be lost.

On the other hand, in die casting, since the molten metal is extruded at high speed by the plunger tip, the wear between the outer peripheral surface of the plunger tip and the inner peripheral surface of the injection sleeve tends to increase. Therefore, the plunger lubricant composition is required to have high lubricity.

In order to satisfy the high lubricity under high temperature and high speed conditions as described above, a solid lubricant is often mixed with the base oil and used. Among the solid lubricants, graphite-based lubricants containing graphite are widely used from the viewpoints of excellent heat resistance and lubricity (Patent Document 1). However, the graphite-based lubricant may contaminate the vicinity of the injection portion at the time of application, deteriorating the working environment, or mixing with the casting and contaminating the product. On the other hand, for the purpose of improving the working environment, the use of non-black solid lubricants such as mica, talc, and kaolin has been attempted (Patent Document 2).

Japanese Unexamined Patent Publication No. 2013-006205 JP-A-2010-174204

However, many of the lubricant compositions using a non-black solid lubricant are inferior in lubricity to the graphite-containing lubricant composition, and have a problem that galling and wear of the plunger tip increase.

An object to be solved by the present invention is to provide a plunger lubricant composition having excellent lubricity under high temperature and high speed conditions while preventing deterioration of the working environment and contamination of the product.

The lubricant composition according to the present invention is a plunger lubricant composition applied between the outer peripheral surface of the plunger tip and the inner peripheral surface of the injection sleeve, and is (A) base oil and (B) barium or. The gist is that it contains one or more selected from strontium sulfates, carbonates, nitrates or chlorides.

The component (B) is preferably one or two selected from barium or strontium sulfates, and more preferably barium sulfate.

The lubricant composition is preferably a water-free oil-based lubricant.

The lubricant composition preferably does not contain graphite.

The barium sulfate is preferably contained in an amount of 1 to 50% by mass.

According to the lubricant composition according to the present invention, since the component (B), which is a non-black solid lubricant, is used, deterioration of the working environment and contamination of the product can be prevented, and even under high temperature and high speed conditions. It has excellent lubricity and can reduce the friction between the plunger tip and the injection sleeve.

The lubricant composition according to the present invention (hereinafter, also referred to as “the present composition”) will be described in detail.

The lubricant composition according to the present invention contains (A) a base oil. The base oil is not particularly limited, and is, for example, a mineral oil typified by a paraffin-based refined distillate obtained by distilling a crude oil, a naphthen-based refined mineral oil, or the like, which is chemically synthesized. Paraffin-based, naphthen-based, olefin-based hydrocarbon-based synthetic oils, ester-based synthetic oils and other synthetic oils, palm oil, corn oil, grape seed oil, coconut oil, cottonseed oil, wheat germ oil, soybean oil Examples thereof include vegetable oils such as saflower oil, olive oil, peanut oil, rapeseed oil and sunflower oil, animal oils such as beef fat and pork fat, and other fats and oils. One of these may be used alone, or two or more of them may be used in combination.

The lubricant composition according to the present invention contains one or more selected from (B) barium or strontium sulfates, carbonates, nitrates or chlorides. From the viewpoint of safety, the component (B) is preferably a sulfate of barium or strontium. Further, from the viewpoint of ease of domestic supply, barium sulfate, carbonate, nitrate or chloride is preferable. From the above, barium sulfate is particularly preferable as the component (B).

The component (B) having a smaller average particle size has better lubricity. The average particle size is preferably 10 μm or less, more preferably 6 μm or less, and particularly preferably 2 μm or less. The lower limit of the average particle size is preferably 0.1 μm or more from the viewpoint of suppressing secondary agglutination.

Barium sulphate and strontium sulphate may be obtained by crushing natural barite or celestine, or chemically synthesized, and either of them may be used. Carbonates, nitrates and chlorides are usually often chemically synthesized. Further, the component (B) may be surface-treated for the purpose of improving dispersibility and the like.

The content of the component (B) is preferably 1 to 50% by mass with respect to the total amount of the composition. More preferably, it is 5 to 30% by mass. When it is 1% by mass or more, the lubricity is excellent. On the other hand, even if it is added in an amount of 30% by mass or more, further improvement in lubricity is not expected, and it is preferably 30% by mass or less from the viewpoint of properties such as excellent coatability.

The component (B) is a white solid lubricant. Other non-black solid lubricants include talc, mica, calcium carbonate, calcium hydroxide, etc., but component (B) is superior in lubricity at high temperatures compared to other non-black lubricants. Therefore, it is suitable as a plunger lubricant composition.

The lubricant composition according to the present invention may contain a solid lubricant other than the component (B) as long as the effect of the present invention is not impaired. Excessive addition of black solid lubricants such as graphite and molybdenum disulfide may deteriorate the working environment and contaminate the product. The content of the black solid lubricant may be appropriately determined according to the permissible range of contamination and the like, but is preferably about 3% by mass or less based on the total amount of the composition.

The lubricant composition according to the present invention may be used as a water-free oil-based lubricant or as a water-containing aqueous lubricant. It is preferably used as an oil-based lubricant from the viewpoint of long-term storage and excellent lubricity. A water-free oil-based lubricant means that water is not intentionally added during the manufacturing process, and may contain a small amount of water that is inevitably mixed during manufacturing or storage.

When used as a water-based lubricant, it becomes a non-dangerous substance, and the degree of stains, ignition, and smoke generation of the product can be suppressed, and the work environment at the site is excellent. When the aqueous lubricant is used, the content of water is not particularly limited, but is preferably 90% by mass or less with respect to the total amount of the composition. At this time, the composition may take any form of emulsion type, soluble type and solution type.

In the lubricant composition according to the present invention, various additives may be added as long as the gist of the present invention is not deviated. Examples of the additive include a dispersant, a surfactant, a viscosity index adjuster, a preservative, a dye, a fragrance, an antifoaming agent, an extreme pressure additive, an anti-wear agent, and an antioxidant.

In actual use, it is preferable to add a dispersant or a surfactant as the above-mentioned additive. The addition of a dispersant or a surfactant is optional, but when these are added, separation and sedimentation of components such as a solid lubricant can be suppressed, and storage stability is excellent.

Since the lubricant composition according to the present invention is excellent in heat resistance and lubricity, it can be suitably used as a plunger lubricant composition. Plunger tips and injection sleeves for die casting and the like are used at high temperatures and high speeds. The present composition is effective as a lubricant for plungers used under such harsh conditions.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

(Preparation of lubricant composition)
(Example 1)
68% by mass of base oil 1 (JXTG Energy's Super Oil N460 (paraffin mineral oil)) and 20% by mass of salad oil (Nisshin Oillio Group's soybean salad oil S), 1% by mass of propylene carbo as a dispersant Nart (manufactured by Kishida Chemical Co., Ltd.) and 1% by mass of organic bentnite (Esben N-400 manufactured by Hojun Co., Ltd.) were added and stirred. 10% by mass of barium sulfate 1 was added little by little and stirred to obtain a lubricant composition.

(Examples 2-9, Comparative Examples 1-13)
This is the same as in Example 1 except that the solid lubricants shown in Tables 1 and 2 were used instead of barium sulfate 1.

(Example 10)
This is the same as in Example 1 except that the base oil 1 is 58% by mass and the barium sulfate is 20% by mass.

(Example 11)
This is the same as in Example 1 except that the base oil 1 is 48% by mass and the barium sulfate is 30% by mass.

(Example 12)
70% by mass water, 10% by mass base oil 2 (JXTG Energy Super Oil N46 (paraffin mineral oil)), 10% by mass salad oil (Nisshin Oillio Group soybean salad oil S), 5% by mass After mixing the surfactant and emulsifying, 5% by mass of barium sulfate 1 was added little by little and stirred to obtain a lubricant composition.

(Comparative Examples 14 to 16)
This is the same as in Example 12 except that the solid lubricant shown in Table 2 was used instead of barium sulfate 1.

(Plane sliding test)
A 3.3 mg / m ² lubricant composition was applied to a test piece (carbon tool steel 30 x 500 x 1.8 mm), and a die (SKD-61 R = 2.5 width 20 mm) was used to create a surface pressure of 8. A plane sliding test was performed under the conditions of 3 MPa, a sliding speed of 400 mm / sec or more, and a sliding distance of 150 mm at room temperature and at a high temperature of 500 ° C. or higher, and the coefficient of friction was measured.

(Solid lubricant)
-Barium sulfate 1: W-1 (barium sulfate) manufactured by Takehara Chemical Industry Co., Ltd. Particle diameter: 2.0 μm
-Barium sulfate 2: W-6 (barium sulfate) manufactured by Takehara Chemical Industry Co., Ltd. Particle diameter: 6.0 μm
-Barium sulfate 3: B-34 (surface-treated sedimenting barium sulfate) manufactured by Sakai Chemical Industry Co., Ltd. Particle size: 0.3 μm
-Barium sulfate 4: Sedimentary barium sulfate 110 (precipitated barium sulfate) manufactured by Sakai Chemical Industry Co., Ltd. Particle size: 0.6 μm
-Barium sulfate 5: BMH-40 (precipitated barium sulfate) manufactured by Sakai Chemical Industry Co., Ltd. Particle diameter: 5.0 μm
-Barium carbonate: BW-E1 manufactured by Sakai Chemical Industry Co., Ltd. Particle diameter: 1.5 μm
・ Barium nitrate: manufactured by Yoneyama Yakuhin Kogyo Co., Ltd. ・ Barium chloride: manufactured by Yoneyama Yakuhin Kogyo Co., Ltd. (anhydrous)
・ Strontium sulfate: manufactured by Wako Pure Chemical Industries, Ltd. ・ Talc 1: manufactured by Japan Talc MS-KY Particle size: 25.0 μm
-Talc 2: Made by Japan Talc SIMGON Particle size: 8.0 μm
-Talc 3: SG-200 manufactured by Nippon Talc Co., Ltd. Particle diameter: 3.2 μm
・ Mica 1: Repco MK-100 (synthetic mica) Particle diameter: 4.0 μm
-Mica 2: Repco M-XF (Muscovite) Particle size: 3.8 μm
・ Mica 3: Repco S-XF (phlogopite) Particle diameter: 3.0 μm
・ Mica 4: Serisite FSN (sericite) manufactured by Sanshin Mining Co., Ltd. Particle diameter: 4.0 μm
・ Calcium carbonate 1: Shiraishi Kogyo Co., Ltd. vigot15 Particle size: 0.15 μm
・ Calcium carbonate 2: Whiten SSB blue manufactured by Shiraishi Kogyo Co., Ltd. Particle diameter: 1.5 μm
・ Calcium hydroxide: Super special slaked lime manufactured by Kondo Lime Industry Co., Ltd. Particle diameter: 9.0 μm
・ Calcium sulfate: Calcium sulfate / dihydrate manufactured by Wako Pure Chemical Industries, Ltd. ・ Magnesium sulfate: Magnesium sulfate (anhydrous) manufactured by Wako Pure Chemical Industries, Ltd.
・ Barium stearate: manufactured by Kawamura Kasei Kogyo Co., Ltd.

From Tables 1 to 3, there is no significant difference in the coefficient of friction at room temperature when a general solid lubricant used for processing oil or the like is used. However, in terms of the coefficient of friction at high temperature, Comparative Examples 1 to 16 which did not contain the solid lubricant of the component (B) were inferior to the examples containing the component (B). In this example, in order to confirm the lubrication performance at high speed, a plane sliding test was conducted under the condition of a sliding speed of 400 mm / sec or more. When the same test is performed at a low speed, the difference in friction coefficient as in this example is not observed even in Comparative Examples 1 to 16 which do not contain the solid lubricant of the component (B).

On the other hand, according to the examples containing the component (B), good lubricity can be obtained under high temperature conditions. In particular, barium sulfate has excellent lubricity and may be either pulverized barium sulfate (Examples 1 and 2) or synthetic barium sulfate (Examples 3 to 5). Good lubricity can be obtained. Further, even a surface-treated product (Example 3) can be used. As the component (B), any of sulfate (Example 1), carbonate (Example 6), nitrate (Example 7), and chloride (Example 8) can provide good lubricity. In particular, sulfates and carbonates have excellent lubricity. Further, even a strontium salt (Example 9) has the same effect as a barium salt. On the other hand, salts of organic acids such as barium stearate (Comparative Example 13) do not have excellent lubricity at high temperatures. It is presumed that this is because the heat resistance is inferior to that of the inorganic salt and it did not function as a solid lubricant under high temperature conditions. From Examples 1 to 2 and 3 to 5, as the component (B), the smaller the average particle size, the better the lubricity.

From Table 3, the lubricant composition according to the present invention containing the component (B) can also be used as an aqueous lubricant containing water. When used as a water-based lubricant, it becomes a non-dangerous substance, and the degree of dirt, ignition, and smoke generation of the product is suppressed, and it is excellent in the work environment at the site. On the other hand, when it is used as an oil-based lubricant as in Examples 1 to 11, it is excellent in long-term storage and lubricity.

Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the above embodiments and examples, and various modifications can be made without departing from the spirit of the present invention. ..

Claims (6)

A plunger lubricant composition comprising (A) a base oil and (B) one or more selected from (B) barium or strontium sulfates, carbonates, nitrates or chlorides. The plunger lubricant composition according to claim 1, wherein the component (B) is one or two selected from barium or strontium sulfate. The plunger lubricant composition according to claim 1 or 2, wherein the component (B) is barium sulfate. The plunger lubricant composition according to any one of claims 1 to 3, wherein the composition is an oil-based lubricant that does not contain water. The plunger lubricant composition according to any one of claims 1 to 4, which is characterized by containing no graphite. The plunger lubricant composition according to any one of claims 1 to 5, wherein the component (B) is contained in an amount of 1 to 50% by mass.